The objectives of this proposal are to investigate several cellular regulatory mechanisms which are operative within certain carbohydrate catabolic pathways in the caries-conducive organisms, Streptococcus mutans. Since glycolysis is the catabolic pathway by which these organisms generate the ATP necessary for biosynthesis and growth, our studies will focus upon the control mechanisms operating within this pathway and within other pathways which ultimately produce a glycolytic intermediate. Cellular control of certain enzyme activities will be studies from the standpoints of regulation of enzyme activity through "feedback" inhibition and allosteric modulation. Specifically, induction and repression studies will be performed upon hexitol phosphate dehydrogenases and alcohol dehydrogenases from S. mutans by determining the specific activities of the enzymes at various growth phases in the presence and absence of inducer. The effect of glucose on enzyme induction will also be determined. Studies dealing with the regulation of enzyme activity will be performed with two constitutive glyceraldehyde-3-phosphate dehydrogenases and two inducible hexitol phosphate dehydrogenases from S. mutans. The enzymes will be partially purified and certain kinetic and physical properties determined. The effect of certain regulatory legends upon these kinetic and physical properties will then be studied.